buckshot type and canister added. now to figure

code/datums/ammo/bullet/shotgun.dm

@@ -35,6 +35,64 @@
 			to_chat(living_mob, SPAN_HIGHDANGER("The impact knocks you off-balance!"))
 		living_mob.apply_stamina_damage(fired_projectile.ammo.damage, fired_projectile.def_zone, ARMOR_BULLET)
 
+/datum/ammo/bullet/shotgun/buckshot/canister
+//constructed with the assistance of vero5123.
+	name = "\improper M108 Canister Grenade"
+	handful_state = "grenade_hedp"
+	icon_state = "buckshot"
+	multiple_handful_name = TRUE
+	bonus_projectiles_type = "/datum/ammo/bullet/shotgun/spread/canister"
+
+	accuracy_var_low = PROJECTILE_VARIANCE_TIER_6
+	accuracy_var_high = PROJECTILE_VARIANCE_TIER_6
+	accurate_range = 5
+	max_range = 8
+	damage = 25
+	penetration = 0
+	shell_speed = AMMO_SPEED_TIER_1
+	damage_armor_punch = 1
+	pen_armor_punch = 0
+	bonus_projectiles_amount = EXTRA_PROJECTILES_TIER_10
+
+/datum/ammo/bullet/shotgun/buckshot/canister/on_hit_mob(mob/M, obj/projectile/P)
+	knockback(M, P, 4)
+	slowdown(M, P)
+
+/datum/ammo/bullet/shotgun/buckshot/canister/set_bullet_traits()
+	. = ..()
+	LAZYADD(traits_to_give, list(
+		BULLET_TRAIT_ENTRY_ID("turfs", /datum/element/bullet_trait_damage_boost, 7, GLOB.damage_boost_turfs),
+		BULLET_TRAIT_ENTRY_ID("breaching", /datum/element/bullet_trait_damage_boost, 12, GLOB.damage_boost_breaching),
+		BULLET_TRAIT_ENTRY_ID("pylons", /datum/element/bullet_trait_damage_boost, 5, GLOB.damage_boost_pylons)
+	))
+
+/datum/ammo/bullet/shotgun/buckshot/canister/spread
+	name = "low velocity canister shot"
+	icon_state = "buckshot"
+
+	accuracy_var_low = PROJECTILE_VARIANCE_TIER_6
+	accuracy_var_high = PROJECTILE_VARIANCE_TIER_6
+	accurate_range = 5
+	max_range = 8
+	damage = 25
+	penetration = 0
+	shell_speed = AMMO_SPEED_TIER_1
+	damage_armor_punch = 1
+	pen_armor_punch = 0
+
+/datum/ammo/bullet/shotgun/spread/canister/on_hit_mob(mob/M, obj/projectile/P)
+	knockback(M, P, 4)
+	slowdown(M, P)
+
+
+/datum/ammo/bullet/shotgun/spread/canister/set_bullet_traits()
+	. = ..()
+	LAZYADD(traits_to_give, list(
+		BULLET_TRAIT_ENTRY_ID("turfs", /datum/element/bullet_trait_damage_boost, 7, GLOB.damage_boost_turfs),
+		BULLET_TRAIT_ENTRY_ID("breaching", /datum/element/bullet_trait_damage_boost, 12, GLOB.damage_boost_breaching),
+		BULLET_TRAIT_ENTRY_ID("pylons", /datum/element/bullet_trait_damage_boost, 5, GLOB.damage_boost_pylons)
+	))
+
 /datum/ammo/bullet/shotgun/beanbag
 	name = "beanbag slug"
 	headshot_state = HEADSHOT_OVERLAY_LIGHT //It's not meant to kill people... but if you put it in your mouth, it will.

code/game/objects/items/explosives/grenades/marines.dm

@@ -130,6 +130,36 @@
 	shrapnel_count = 56
 	falloff_mode = EXPLOSION_FALLOFF_SHAPE_LINEAR
 
+
+ /*
+//================================================
+				Canister Grenades
+//================================================
+Special thanks to vero5123 for making this work. He, uh, basically put this all together in an hour??? -koishi
+*/
+/obj/item/explosive/grenade/high_explosive/airburst/canister
+	name = "\improper M108 canister grenade"
+	desc = "30mm canister grenade, effectively low velocity buckshot. Substantial close combat impact when paired with the 5 round PN pump action grenade launcher. No, you can't set it off with a hammer, moron."
+	icon_state = "grenade"
+	item_state = "grenade_hedp"
+	hand_throwable = FALSE
+	underslug_launchable = TRUE
+	explosion_power = 0
+	explosion_falloff = 25
+	det_time = 0 //this should mean that it will explode instantly when fired and thus generate the shotshell effect.
+	shrapnel_count = 20
+	shrapnel_type = /datum/ammo/bullet/shotgun/buckshot/canister
+	dispersion_angle = 20 //hopefully this means the cone spread is pretty small
+/obj/item/explosive/grenade/high_explosive/airburst/canister/proc/canister_fire(obj/item/weapon/gun/launcher/grenade/gl, target)
+	var/direction = Get_Compass_Dir(gl, target)
+	var/position = get_step(gl, direction) //otherwise we buckshot ourselves
+	create_shrapnel(position, min(direct_hit_shrapnel, shrapnel_count), direction , dispersion_angle, shrapnel_type, cause_data, FALSE, 100)
+	if(shrapnel_count)
+		create_shrapnel(loc, shrapnel_count, direction, dispersion_angle, shrapnel_type, cause_data, FALSE, 0)
+	qdel(src)
+// canister has no impact explosion.
+/obj/item/explosive/grenade/high_explosive/airburst/canister/launch_impact(atom/hit_atom)
+	return
 /*
 //================================================
 				Airburst Grenades

code/game/objects/items/storage/boxes.dm

@@ -631,6 +631,17 @@
 	grenade_type = /obj/item/explosive/grenade/phosphorus
 	has_gamemode_skin = FALSE
 
+/obj/item/storage/box/nade_box/canister
+	name = "\improper M108 canister grenade box"
+	desc = "Reinforced box of 25 30mm M108 canister grenades."
+	icon_state = "airburst_nade_placeholder" //ill get a sprite done for this
+	w_class = SIZE_LARGE
+	storage_slots = 25
+	max_storage_space = 25
+	can_hold = list(/obj/item/explosive/grenade/high_explosive/airburst/canister)
+	grenade_type = /obj/item/explosive/grenade/high_explosive/airburst/canister
+	has_gamemode_skin = FALSE
+
 /obj/item/storage/box/nade_box/airburst
 	name = "\improper M74 AGM-F grenade box"
 	desc = "A secure box holding 25 M74 AGM Fragmentation grenades. Explosive, don't store near the flamer fuel."

code/modules/projectiles/guns/specialist/launcher/grenade_launcher.dm

@@ -195,6 +195,13 @@
 	msg_admin_attack("[key_name_admin(user)] fired a grenade ([fired.name]) from \a ([name]).")
 	log_game("[key_name_admin(user)] used a grenade ([name]).")
 
+	// canister rounds explode before leaving the barrel of the launcher.
+	// section constructed by vero5123.
+	if(istype(fired, /obj/item/explosive/grenade/high_explosive/airburst/canister))
+		var/obj/item/explosive/grenade/high_explosive/airburst/canister/canister_round = fired
+		canister_round.canister_fire(src, target)
+		return
+
 	fired.throw_range = 20
 	fired.det_time = min(10, fired.det_time)
 	fired.activate(user, FALSE)